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IGNITION CIRCUIT SWITCH Filed Jan. 28, 1928 2 4/ 2a 36 a? I 20 4% illl W 4 /2 A? I 'fi illllll 39 L I *T 'i INVENTOR THO MAS H.THO MAS ATTORNEY Patented Sept. 10, 1929.

UNITED STATES PATENT OFFICE.

THOMAS H. THOMAS, OF EDGEWOOD, PENNSYLVANIA, ASSIGNOB TO THE WESTING- HOUSE AIR BRAKE COMPANY, OF WILKEBDING, PENNSYLVANIA, A CORPORATION 01 PENNSYLVANIA.

IGNITION-CIRCUIT SWITCH.

Application filed January 28, 1928. Serial No. 250,225.

This invention relates to motor vehicles, and more particularly to the type equipped with an internal combustion engine for driving the vehicle and having the usual electric 5 ignition circuit.

The principal object of my invention is to provide means operated upon applying the brakes for opening the engine ignition circuit, so as to cut off power when the brakes are applied.

In the accompanying drawing, the single figure is a diagrammatic view, partly in section, of a motor vehicle equipment embodying my invention.

As shown in the drawing, the apparatus comprises a switch device 1, interposed in the primary circuit of an ignition system, such as used with the usual type of internal combustion engine, and adapted to be pneumati- '20 cally operated by a brake application valve device 2. Included in said primary circuit is the usual battery or source of current supply 3, ignition coil 4, circuit breaker mec anism 5, ammeter 6, and manually operated switch 7.

The switch device 1 comprises a casing having a chamber 8 connected to the application valve device 2 through a passage and pipe 9 and containing a piston 10, having a stem 11 extending upwardly through a dividing wall 12 andinto a chamber 13. Carried by the stem 11 is a switch member 14, which is interposed between two insulating washers 15. The switch member 14 and the 5 washer 15 are clamped against a shoulder 16 on said stem by a nut 44. An extension 17 of the stem 11, of reduced diameter, extends through the upper wall of chamber 13 and has a button 18 secured thereto at the outer end.

A spring 19 urges the piston downwardly to a position in which the switch member 14 bridges two fixed contacts 20, said contacts being mounted in insulating sleeves 21, se-

cured in the side walls of chamber 13.

A seat ring 22, on the lower side of the piston 10, is adapted to engage with a gasket 23, when the piston is in the lower position, and with the piston in the upper position, a

seat ring 24 in the casing is adapted to engage a seat 25 mounted in the upper face of the iston.

T e application valve device 2 comprises a cas1ng having a chamber 26 containing a p ston 27, and a chamber 28 containing a sl de valve 29 adapted to be operated by said piston, said chamber 28 being connected to a volume reservoir 30 through a passage and p pe 31. A spring 32, also contained in the p ston chamber 26, urges the piston 27 and slide valve 29 toward the normal position, as shown in the drawing.

The ignition coil 4 is of the usual induction type having a primary and a secondary wlnding, the primary winding bein connected as shown in the drawing and t e secondary winding being connected to the usual spark plugs (not shown) in the cylinder head of the engine.

The circuit breaker mechanism 5 is of the usual type having a cam 33 adapted to be rotated in certain timed relation to the rec procating parts (not shown) in the eng ne and to operate an arm 34, pivoted on a p n 35, in order to alternately connect and disconnect a movable contact 36 on thearm 34 and a stationary contact 37.

The brake equipment may be of the type in which the pipe 38 of the application valve device 2 is adapted to be normally charged with fluid under pressure and having means whereby when the operator becomes disabled, fluid under pressure is vented from the pipe 38.

When pipe 38 is charged with fluid under pressure, piston chamber 26 is also charged and fluid flows from said chamber through port 40 in piston 27 to valve chamber 28, charging said valve chamber, as well as the volume reservoir 30, with fluid under pressure. With the fluid pressures substantially equal on the opposite sides of said piston, the pressure of spring 32 maintains said piston and slide valve 29 in the position shown in the drawing, in which position the switch piston chamber 8 is vented to the atmosphere through pipe and passage 9, cavity 41 in the slide valve 29 and the atmospheric passage 42. With said switch piston chamber thus vented, spring 19 maintains piston 10 in its downward position, .in which the switch 'member 14 bridges .the contacts 20, so that the primary circuit of the ignition system is closed at the switch device 1.

With the ignition circuit closed, by operation of the manually operated switch 7, and the engine (not shown) running, it the fluid under pressure is vented from the piston chamber 26 throughthe pipe 38, the fluid pressure in valve chamber 28 then shifts the piston 27 and slide valve 29 outwardly against spring'32, to a position in which a port 43 through the slide valve re 'sters with passage 9, thereby permitting uid under pressure to flow from the valve chamber 28 and reservoir 30 to the area inside the seat ring 22 on the switch piston 10. When a certain pressure is thus built up on the inner area of said piston, the piston starts moving upwardly and breaks the seal between the seat ring 22 and gasket 23, thereby'exposing the full lower face of the piston to the pressure of said fluid. Said piston is thereby promptly moved up until it seals against the 5 seat ring '24 in the casing, such movement shifting the switch member 14 away from the contacts 20, thereby opening the primary circuit of the ignition system and causing the engine to stop. 1

With the pipe 38 open to the atmosphere, fluid under pressure in valve chamber 28 and in the reservoir 30, as well as in the switch piston chamber 8, blows down through port 40 in the application valve piston 27, and when the pressure in chamber 8 is reduced to a predetermined low degree, the

pressure of spring 19 returns the switch pis-.

ton and switch 14 to the normal position, in which the primary circuit of the ignition system is again closed by connecting the contacts 20 through said switch, so that the engine may be again started, if desired. The flow capacity of the port 40 is such as to ensure that the primary circuit cannot be closed, until after the vehicle is completely stopped.

In some cases, it may not be desired to have the switch 14 automatically close the primary circuit, in the manner above described. If it be preferred that the circuit be not closed automatically, the spring 19, acting on the piston 10, may be omitted, in which case the switch 14 will remain in open position until manually closed by pressing down the push button 18.

While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims. 1 7

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is

1. In a motor vehicle equipment, the combination with a motor ignition circuit, of a fluid pressure operated switch device for com 1 -to sai rgvaaaee trolling the ignition circuit, and means operated upon applying the brakes on the vehicle for sup lying fluid under pressure tosaid switch evice.

2. In a motor vehicle equipment, the combination with a motor ignition circuit, of a fluid pressure operated switch device for controlling'the i' ition circuit, and avalve device for eflecting an application of the brakes and adapted in one position to connect said switch device to the atmos here and in another (position to supply fluld under pressure switch device.

\ 3. In a motor vehicle equipment, the combination with a motor ignition circuit of a fluid pressure operated switch device for controlling the i 'tion circuit,-and a valve device for eflecting an application of the brakes and adapted in release position to connect said switch device to the atmosphere and in brake application position to supply fluid under pressure-to said switch device to operate said switch device to open the ignition circuit.

4. In a motor-vehicle equipment, the combination with a motor ignition circuit, of a fluid pressure operated switch device for controlling the ignition circuit, and a valve device operated upon a reduction in fluid pressure for eflecting an a plication of the brakes and for supplymg u1d under pressure to said switch device to thereby operate said switch device to-open the ignition circuit.

In testimony whereof I have hereu nto set myhand.

. THOMAS H. THOMAS 

